Hexapoda: Comparative aspects of later embryogenesis and metamorphosis

Abstract

Arthropods are the most species-rich phylum. Within arthropods, species diversity is concentrated in the Hexapoda, which includes on the order of one million described species. The ancestor of hexapods was among the first metazoan lineages to move into a terrestrial environment. Hexapods were also the first lineage to evolve powered flight and remain the only invertebrate lineage to have done so. Hexapods are both exceptionally abundant in many habitats and exceptionally diverse ecologically, with lifestyles ranging from parasitic to agricultural. They also show extensive coevolutionary histories with other taxa, especially flowering plants, which hexapods both pollinate and consume. All of this diversity is achieved within a highly conserved body plan consisting of a segmented head, thorax, and abdomen, which bear an assortment of jointed appendages.